docs: def get_role_arn(role_name, env, region):
      """Get role ARN given role name.
  
      Args:
          role_name (str): Role name to lookup
          env (str): Environment in which to lookup
          region (str): Region
  
      Returns:
          ARN if role found
  
      """
      session = boto3.Session(profile_name=env, region_name=region)
      iam_client = session.client('iam')
  
      LOG.debug('Searching for %s.', role_name)
  
      role = iam_client.get_role(RoleName=role_name)
      role_arn = role['Role']['Arn']
  
      LOG.debug("Found role's %s ARN %s", role_name, role_arn)
  
      return role_arn